This coloring agent is 5-hydroxy-1-p-sulfophenyl-4-(p-sulfophenylazo)-pyrazol-3-carboxylic acid, trisodium salf (Figure 9.12). It is a yellow powder and has been used as a food coloring additive since 1916.
The median acute oral lethal dose of the diet for 2 years without adverse effects, with the possible exception of pyloric gastritis in one dog. Tumor incidence was unchanged relative to controls in rats receiving tartrazine at 1.5% of the diet for 64 weeks and in rats administered this dye at 5.0% of the diet for 2 years.